1. Technical Field
The present disclosure relates to a mold that can prevent a core insert from deviating from a correct path of travel when driven by an ejection mechanism.
2. Description of Related Art
Referring to FIG. 1, a conventional mold 40 includes a core insert 41, a cavity plate 42, a support plate 43, a core plate 44, a cavity plate 45, and an ejection mechanism 30 to eject the core insert 41. The support plate 43 is attached to the core plate 44, and the core insert 41 is movably received in the core plate 44. The core insert 41 defines a first molding surface 410. The cavity insert 45 is received in the cavity plate 42, and defines a second molding surface 450. When the first molding surface 410 and the second molding surface 450 are brought into contact with each other, they cooperatively define a molding cavity therebetween for molding one or more products or items.
The ejection mechanism 30 includes a top plate 31, a bottom plate 32, an ejection member 33, a washer 34, and a fastener 35. The top plate 31 defines a first fastening hole 310 facing toward the bottom plate 32. The bottom plate 32 defines a first through hole 320. One (top) end of the ejection member 33 is received in the first through hole 320. An opposite (bottom) end of the ejection member 33 is movably received in the support plate 43, and always stays in contact with the core insert 41. The top end of the ejection member 33 defines a second fastening hole 330 aligning with the first fastening hole 310. The washer 34 is disposed between the top plate 31 and the bottom plate 32, and defines a second through hole 340 communicating with the first fastening hole 310 and the first through hole 320. The fastener 35 is screwed into the first fastening hole 310, and into the second fastening hole 330 through the second through hole 340, to fasten the top plate 31 and the ejection member 33 together.
When the mold 40 is in use, in an exemplary first stage of operation, the core plate 44 and the cavity plate 42 are separate from each other, with the core insert 41 in the core plate 44 in a retracted position. This initial state is illustrated in FIG. 1.
In a second stage of operation, the core plate 44 and the cavity plate 42 are moved into contact with each other, such that the first molding surface 410 is brought into contact with the second molding surface 450. In this position, molten material between the first and second molding surfaces 410, 450 is used to make the molded products. It is important for the first and second molding surfaces 410, 450 to be in precise contact with each other to ensure accurate molding.
In a third stage of operation, the core plate 44 and the cavity plate 42 are moved to separate from each other, and simultaneously the top plate 31 drives the ejection member 33 down to push the core insert 41 down from the retracted position to an extended position in which the core insert 41 projects from the core plate 44 to a maximum extent. (This is known in the art as “ejecting” the core insert 41.) Throughout this time, the first and second molding surfaces 410, 450 remain in contact with each other.
After that, the core plate 44 and the cavity plate 42 are moved to separate from each other, and simultaneously the top plate 31 drives the ejection member 33 up such that the core insert 41 moves back up to the retracted position in the core plate 44 (as illustrated in FIG. 1). The first and second molding surfaces 410, 450 are thus detached from each other, so that the molded products can be obtained.
For each molding cycle as described above, the top plate 31 drives the ejection member 33 down and then up. After the mold 40 has been used repeatedly over a long time, the ejection mechanism 30 is liable to become worn. In particular, the ejection member 33 is liable to deviate (deflect) from travel along an exact vertical path, and is liable to cause the core insert 41 to be incorrectly oriented off-axis (i.e., deviating from the vertical). This means that when the first molding surface 410 is brought into contact with the second molding surface 450, the first molding surface 410 is liable to deviate (deflect) relative to the second molding surface 450. An unwanted gap is thus created between the first molding surface 410 and the second molding surface 450. Molten plastic can flow into the gap, thereby adversely affecting the quality of the molded products
Therefore, what is needed is a mold to overcome the shortcomings described above.